Date: Thu, 25 Aug 2011 15:52:59 +0000 From: "b. f." <bf1783@googlemail.com> To: freebsd-current@FreeBSD.org, George Neville-Neil <gnn@neville-neil.com>, "Bjoern A. Zeeb" <bzeeb-lists@lists.zabbadoz.net> Subject: Re: Updating our TCP and socket sysctl values... Message-ID: <CAGFTUwNLfmVYjP0MtHyi4RYCsUH_SJzhgte7zxeNY%2BzRYiuxUA@mail.gmail.com>
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> >> I believe it's time to up these values to something that's in line with higher speed > >> local networks, such as 10G. Perhaps it's time to move these to 2MB instead of 256K. > >> > >> Thoughts? > > > > > > This never happened, did it? Was there a reason? > > > > I went back and looked at the mail thread. I didn't see any strong objections > so I think you should commit this for 9.x. > > np@ did point out that nmbclusters also lags on modern hardware so consider upping > that at the same time. I thought Bruce's observation, in: http://lists.freebsd.org/pipermail/freebsd-arch/2011-March/011193.html that: "...there is an mostly-unrelated bufferbloat problem that is purely local. If you have a buffer that is larger than an Ln cache (or about half than), then actually using just a single buffer of that size guarantees thrashing of the Ln cache, so that almost every memory access is an Ln cache miss. Even with current hardware, a buffer of size 256K will thrash most L1 caches and a buffer of size a few MB will thrash most L2 caches." , and his suggestion for some sort of auto-tuning, deserve consideration. Are you going to address this problem (at least the L2 and higher cache thrashing), or give some suggestions for tuning in UPDATING and the relevant manpages? b.home | help
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